Process for refining vegetable oils



Patented Nov. 1, ,1932

PATENT OFFICE UNITED STATES LUDWIG ROSENSTEIN AND WALTER J. HUND, OF SAN FRANCISCO, CALIIIORN I;.

PROCESS I93 BEF INING VEGETABLE OILS Ho Drawing.

This invention relates to a process for the refining f natural organic products such as vegetable and animal oils, fats, waxes and the like such as cocoanut oil, cotton seed oil, and

More specifically it consists of refining these organic products with alkylolamines and especially ethanolamines or mixtures thereof with ammonia.

The invention possesses numerous advantageous features and objects, some of which will appear in full in the following description in which we have outlined our invention. It is understood that the invention, as defined by the claims, is to be accorded a range of mechanical and chemical equivalents consistent with the state of the prior art.

It is our discovery that the organic mate rials, can be refined-of impurities comprising usually free fatty acids, coloring matter, aldehydes, and other substances, by-the use of normally liquid compounds of the group known as alkylo'lamines of which mono-, di-, andtri-ethanol amines maybe considered as 5 .the first members as the corresponding methanol compounds are unstable. These compounds may be considered as the ammonia substitution compounds in which one or more of the hydrogen atoms of the am- 0 monia are replaced with the correspondin number of alkylhydroxyl groups (-ROH) These compounds may be used as pure substances, as varying mixtures of group-memhere, or as mixtures of group-mem We have found that. alkylolamines and ammonia are miscible inbers with ammonia.

all proportions, andsuch mixtures have in certain cases distinct advantages. In our copending application, Serial No. 531,650, we have described a refining process'employing liquid ammonia as a treating agent. Taking into consideration the cost of the liquid ammonia as compared to the cost of alkylolamines and the somewhat superior properties The utilization of alkylolamines alone or of certain alkylolamines as refining agents,-

Application filed August 21, 1931. Serial No. 558,558.

with the ammonia is toour knowledge a new and useful improvement in the existing art.

The alkylolamines are in many cases better solvents than ammonia for fatty acids and other impurities while the glycerides, waxes etc. are generally less soluble therein than in ammonia; and as their boiling points are -much higher than that of ammonia the use very insoluble in mono, di-, or tri-ethanol amines or mixtures thereof, while the free fatty acids, colorin matter, aldehydic and nitrogen containingdiodies are very soluble in 0 these alkylolamines, and can be removed from the vegetable oils by extraction with a predetermined quantity of the extracting agent and separation of the two layers thereb formed. The extracting agents ma' be rea m I ily recovered by distillation, pro erably in vacuum and with the aid of some superheated steam, wherebythe ethanolamine soaps are dissociated, and ethanolamines are sepag rated from the extracted impuritiesand recovered with high efiiciency. The recovered alkylolamines may contain some undissociated soap without deleterious efiects on the process. The refined oil after separation from the ethanolamine layer may still contain a small quantity thereof To insure complete removal thereof from the oil the latter may be heated in vacuum and blown with an inert gas, or still better, contacted an with water which dissolves and thus removes ethanolamines, or compounds formed by reactions between ethanolamines and fatty acids or other impurities.

While mono-, di-, or tri-ethanolamines may 8 be used individually or as a mixture, we prefer to operate with substantially monoethanolamine because in general its boiling point is lower than that of the di-, or tricompounds, so that it can be recovered more of the usual type wherein substantially pure readily at a lower temperature of distillation and without .decom osition. As an example of how the process of our invention may be utilized in connection with an oil, such'as cotton seed oil, we shall set forth the separation of the system into two phases;

this takes place more rapidly the lowerthe viscosities of the involved liquids. The two phases are allowed to separate, and it will be found that the oil phase is now of thecolor generally specified by U. S. Pharmacopoeia for sweet oil and is neutral and pleasant to the taste.

The monoethanolamine layer is transferred to a suitable equipment wherein high vacuum may be maintained, say about 25-30 mm. mercury; heat is a plied and a current of superheated steam avin a temperature of about 120 C. is passed t hrough the liquid. The vapors pass through a rectifying column monoethanolamine is separated from water (resulting from the condensation of steam) by fractionation, the water being moved at the top of the column and the monoethanolamine at the bottom. The latter is returned to the system forfurther extraction, while .the fatty acid and other extracted impurities remain in thestill and are available for recovery if desired. 7 v,

This process of refining vegetable oil and the like may be operated as a continuous cycle wherein the material to be purified is treated countercurrently. with the alkylolamine extracting agent.

It will be obvious thatthe temperature of treating must be so chosen that the material to purified is in the liquid state. For c'ocoanut oil this temperatureis about C. It is also advantageous to choose the temperature suitable for rapid-separation of phases, this depending on the viscosities and the difference in specific gravities of phases. 1

It is to be understood that the extracting agents intended for use here, suchas monoethanolamine, when commercially manufactured are not pure substances but represent mixtures in which the desired substance predominates to various degrees for different cases. v

mines may contain 5%, approximately, of water ;the presence of which in such-amounts 1s not detrlmental to the process. Larger amounts in many cases cause excessive emulsification and consequent difficulty insepar ating the layers and should be avoided. The

As commercially obtained, the ethanola-y actual amount of water which may be tolerated depends on the character of the material undergoing treatment. In general we prefer to work with substantiallyvnhydrous alkylolamines. p We claim as our invention:

1. In a process of purifying a substance of the class consisting of oils, fats and waxes of the ester type, the step which comprises contacting the material to be treated with an' allrylolamine.

I 2. In a process of purifying a substance of the class consisting of oils, fats and waxes of the ester type, the step which comprises contacting he material to be treated with an I alkylolamine at an elevated temperature at which said material is a liquid.

3. The process of purifying a substance of the classconsisting of oils, fats and waxes of. the ester type which comprises extracting the impurities from the material 'to be treated by contacting it with an alkylolamine, physically separating said alkylolamine containing extractedv impurities from the material being treated, and treating said material tocomplete the removal of alkylolamine therefrom.

4. The process of purifying a substance of the class consisting of oils, fats and waxes of the ester type which comprises extracting the impurities .from the material to be treated by contacting it with an alkylolamine, physically separating said alkylolamine containin extracted impurities from the material.

being treatedand heating said material under reduced pressure.

v 5. The processof purifying a substance of the class consisting of oils, fats'and waxes of the ester type which comprises extracting the impurities from the material to be treated by contacting it with an alkylolamine, physically separating said alkylolamine contaming extracted impurities from the material being. treated, heating saidrmaterial, and.

blowing it withan inert as.

the class consisting. of oils, fats and waxes of the ester type which comprises extracting the impurities from the material to be treated by contacting it with an alkylolamine, physically separating said alkylolamine conta1ning extracted impurities from the material being treated, water washing the'latter, and physlcally separating the water phase therefrom. Y

7. The process of purifying a substance of the class consisting of oils, fats anl. waxes of .the ester type which comprises extracting the impurities-from'the material to be treated I) contacting it with an alkylolamine, physica l ly separating said alkylolamine containing extracted impurities from the material being 1 treated, and recovering alkylolamine by distillation.

' 8,-The cyclic process of purifying a sub- 11o 6; The process of-puri ying a substance of naeasae. a

stance of the class consisting of oils, fats and contactin the material to treated with a waxes of theester type at a temperature at tri-alkylo mine. which material to be purified is a liquid, by a treating a continuous. flow of the material to.

be purified with a flow of alkylolamine,

-- physically separating the latter together I with dissolved impurities from the .material being treated; recovering the alkylolamine and returning the same to the process.

19 9. In a process of purifying a substance of v the class consisting, of oils, fats and waxes of the ester type, the step which comprises contacting the material to be treated with an ethanolamine. i

10. In a process of purifying a substance of the class consisting of oils, fats and waxes of the ester type, the step which comprises contacting the, material to he treated witho'an ethanolamine atan elevated temperature at which said material is ali uid.

11. The cyclic process 0 purifying a substance of the class consisting of oils, fats and waxes of the ester type at a temperature at.

which material to be purified is a liquid, by treating a continuousflow of the material to be purified with a flow of ethanolamine,

physically separating'the latter together with dissolved impurities from the material being treated, recovering the ethanolamine and returning the same to the-process.

12. Ina process of'purifying a substance of the class consisting of oils, fats and waxes of the ester 'type, the step which comprises monoethanolamine.

13. In a process of purifying a substance of the class consisting of oils, fats andwaxes ofthe ester type, the step which comprises contacting the material .to be treated with a mixture ofjalkylolamine and ammonia,

lfl. Thec-yclic process ofpurifyin a sub stance of the class consisting of oils, ats and waxes of the ester type at a temperature at which material to be purified is a liquid, by

said mixture together with dissolved impurities from the material-being treated; recoverturning the'same to the process; Y e y 15. In a process of purifying a substance of the class consisting ofoils, fats and waxes ing the alkylolamine and ammonia and re v of the ester type, the step which comprises contacting the material to be treated with a mono-alkylolamine.

-' 16. In a process of'purifying a substance of the class consisting of oils, fats and waxes v of the'ester type, thestep which comprises contacting the material to be treated with a di-alkylolamine. p

:17. In a process of purifying a substance of the class consisting of oils, fats and 'waxes $5 of the ester type, the step whichcomprises e have hereunto UDWIG ROSENSTEIN." 1o WALTER J. HUND;

In testimony set our han contacting the material to be treated with 

